Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate carpet and padding needed in square yards, the unit carpet is priced and sold in.
Carpet is priced and sold by the square yard, not the square foot, and padding (sold separately) typically doesn't need the same roll-width waste allowance carpet itself does since it's cut more flexibly. This calculator converts your room's area into both figures correctly.
Enter your room's area in square feet and a waste factor for the carpet itself (10% is a common default, accounting for roll-width seams and pattern matching).
Carpet (sq yd) = (Area × (1 + Waste Factor)) ÷ 9
Padding (sq yd) = Area ÷ 9 (no roll-width waste allowance needed)
Carpet is cut from wide rolls and needs extra material for seam placement and pattern/pile-direction matching across a room -- padding is more flexible to cut and typically doesn't carry the same waste penalty.
Use the resulting square yardage directly with your carpet retailer's per-square-yard pricing to budget your project.
Because carpet is priced by the square yard, the conversion divides square feet by 9. If your measurement is in feet, multiply length by width first, then divide. For example, a 12 by 15 foot room is 180 square feet, or 20 square yards before waste. Getting this step wrong is the most common budgeting error, since the price per square yard seems small next to a price per square foot for other flooring, but it is a different unit and the total is what matters.
Imagine two bedrooms and a hallway totaling 420 square feet, with 10 percent waste (hypothetical values). Carpet is 420 times 1.10, or 462 square feet, divided by 9, which is 51.33 square yards. Padding is 420 divided by 9, or 46.67 square yards. If the carpet is quoted at 25 per square yard installed, the carpet portion would be about 1,283, before padding and other charges. The point of the example is the process: convert to yards, add waste to carpet only, and price each item separately.
For roll-width purchase quantity in a room, the Vinyl Flooring Calculator shows how strips consume material, and the same principle applies to carpet. For a large or complicated space, ask the carpet retailer to make a seam diagram.
Stairs are more complicated than the area formula suggests, because each step has a tread and a riser, and the carpet wraps or waterfalls over the nose. Measure the stairs separately with the retailer, or add the tread and riser depth for each step, multiply by width, and add extra for waste. Rooms with curved walls, bay windows, or many closets typically need a higher waste factor than the default.
The calculator uses a single waste percentage, and does not know your exact roll width, seam plan, or pile direction. Treat the result as a starting point, then have the installer confirm before ordering. Tack strips, seam tape, and transitions are extra.
It's an industry convention tied to how carpet rolls are manufactured and cut -- 1 square yard equals 9 square feet.
No -- padding is generally cut more flexibly and doesn't carry the same roll-width seam and pattern-matching waste that carpet does.
There are 9 square feet in a square yard, since a yard is 3 feet on each side.
Enter your measured room area. The calculator adds waste for the carpet and leaves the padding without it.
Not directly. Stairs need their own measurement, including treads and risers, so ask the retailer or installer to size them.
Retailers account for roll width, seam layout, and pattern matching, which can add more than the standard 10 percent waste.